The invention relates to a device for end position damping of the piston stroke in a pressurized fluid cylinder of the kind comprising a closure member connected to the piston and adapted to enter during a damping process into an outlet opening in front of the piston, and a ring serving as a non-return valve and arranged with an axial play in an annular groove so as to choke the flow of pressurized fluid through the annular passage between the wall defining the outlet opening and the closure member, while permitting a fluid flow in the opposite direction during the return stroke of the piston.
Such a device is known from the Swedish patent specification No. 347,046. In the known device, the ring serving as a non-return valve is formed with a non-deformable cross section, and in order to facilitate its climbing and resilient engagement onto the slightly tapered surface of a closure member or an outlet opening, respectively, the ring is slotted, i.e. circumferentially broken. However, this results in a rather intense friction between the ring and said surface, and there is a risk of obliquity, biting and extensive wear.
In order to enable a sufficiently large fluid flow during the return stroke, certain channels (indicated by the reference numeral 14 in the patent specification) are formed from the bottom of the annular groove through the adjacent wall into the cylinder chamber in front of the piston. These return flow channels represent a structural complication and make the manufacture more difficult and expensive.